Claudia Stielow

Publications of Claudia Stielow

• NO-mediated regulation of NAD(P)H oxidase by laminar shear stress in human endothelial cells.

  Authors: Nicole Duerrschmidt, Claudia Stielow, Gregor Muller, Patrick J Pagano, Henning Morawietz

  The Journal of physiology. 11/2006; 576(Pt 2):557-67.

  The flowing blood generates shear stress at the endothelial cell surface. In endothelial cells, NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (.O(2)(-))The flowing blood generates shear stress at the endothelial cell surface. In endothelial cells, NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (.O(2)(-)) formation. In this study, we analysed the effect of laminar shear stress on .O(2)(-) formation by cytochrome c reduction assay and on NAD(P)H oxidase subunit expression by standard calibrated competitive reverse transcription-polymerase chain reaction and Western blot in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were exposed to laminar shear stress in a cone-and-plate viscometer for up to 24 h. Short-term application of shear stress transiently induced .O(2)(-) formation. This was inhibited by NAD(P)H oxidase inhibitor gp91ds-tat, but NAD(P)H oxidase subunit expression was unchanged. Long-term arterial laminar shear stress (30 dyne cm(-2), 24 h) down-regulated .O(2)(-) formation, and mRNA and protein expression of NAD(P)H oxidase subunits Nox2/gp91(phox) and p47(phox). In parallel, endothelial NO formation and eNOS, but not Cu/Zn SOD, protein expression was increased. Down-regulation of .O(2)(-) formation, gp91(phox) and p47(phox) expression by long-term laminar shear stress was blocked by l-NAME. NO donor DETA-NO down-regulates .O(2)(-) formation, gp91(phox) and p47(phox) expression in static cultures. In conclusion, our data suggest a transient activation of .O(2)(-) formation by short-term shear stress, followed by a down-regulation of endothelial NAD(P)H oxidase in response to long-term laminar shear stress. NO-mediated down-regulation by shear stress preferentially affects the gp91(phox)/p47(phox)-containing NAD(P)H oxidase complex. This mechanism might contribute to the regulation of endothelial NO/.O(2)(-) balance and the vasoprotective potential of physiological levels of laminar shear stress.

• Novel Nox inhibitor of oxLDL-induced reactive oxygen species formation in human endothelial cells.

  Authors: Claudia Stielow, Rusan A Catar, Gregor Muller, Kirstin Wingler, Peter Scheurer, Harald H H W Schmidt, Henning Morawietz

  Biochemical and biophysical research communications. 05/2006; 344(1):200-5.

  In this study, we investigated effects of a novel NAD(P)H oxidase (Nox)-inhibitor 3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine (VAS2870) on oxidized low-density lipoproteinIn this study, we investigated effects of a novel NAD(P)H oxidase (Nox)-inhibitor 3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine (VAS2870) on oxidized low-density lipoprotein (oxLDL)-mediated reactive oxygen species (ROS) formation in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were cultured to confluence and ROS formation was induced with 50microg/ml oxLDL for 2h. ROS formation was detected by chemiluminescence (CL) using the Diogenes reagent. OxLDL induced ROS formation in human endothelial cells (171+/-12%; n=10, P<0.05 vs. control). This augmented ROS formation in response to oxLDL was completely inhibited by the Nox inhibitor VAS2870 (101+/-9%; n=7, P<0.05 vs. oxLDL). Similar results were obtained with superoxide dismutase (91+/-7%; n=7, P<0.05 vs. oxLDL). However, the Nox4 mRNA expression level was neither changed by oxLDL nor VAS2870. We conclude that VAS2870 could provide a novel strategy to inhibit the augmented endothelial superoxide anion formation in response to cardiovascular risk factors.